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Modeling the Focusing Stage of an Electrokinetic Valve

In this video, we simulate an electrokinetic valve. Using the Transport of Diluted Species, Creeping Flow, and Electric Currents interfaces, this video shows the complete analysis of a typical microfluidic valve design. This example is divided into two parts: the focusing stage (shown here) and the injection stage (shown in a follow-up video). During the focusing stage, an ionic sample solution and buffer solution are forced into two microchannels at a constant rate. Once a steady-state profile is reached, the device turns off the pressure-driven flow, completing the focusing stage. At this point, there is a focused concentration profile at the junction of the two microchannels called "the focusing zone". In the follow-up video, which shows the injection stage, electric currents are applied along the microchannels, driving ions from the focusing zone into the injection channel of the electrokinetic valve. Watch the second video,Modeling the Injection Stage of an Electrokinetic Valve

In this video, we simulate an electrokinetic valve. Using the Transport of Diluted Species, Creeping Flow, and Electric Currents interfaces, this video shows the complete analysis of a typical microfluidic valve design. This example is divided into two parts: the focusing stage (shown here) and the injection stage (shown in a follow-up video). During the focusing stage, an ionic sample solution and buffer solution are forced into two microchannels at a constant rate. Once a steady-state profile is reached, the device turns off the pressure-driven flow, completing the focusing stage. At this point, there is a focused concentration profile at the junction of the two microchannels called "the focusing zone". In the follow-up video, which shows the injection stage, electric currents are applied along the microchannels, driving ions from the focusing zone into the injection channel of the electrokinetic valve.

Microfluidics Module

Veryst Engineering, a company that provides consulting in engineering design and product manufacturing, has collaborated with Nordson EFD, one of the leading manufacturers of precision dispensing systems, to optimize their static mixers.
Static mixers are inexpensive and efficient mechanisms for mixing laminar viscous fluids, where molecular ...

Professor Mark Reed and his team at Yale University are using COMSOL Multiphysics to develop a MEMS-based solution for detecting bacteria in blood. Called the aScreen, it will provide analyses speedily, accurately, and cost-effectively. Such a device would greatly help the food industry in improving meat quality and reducing the risk for ...

In many medical procedures and tests, it is necessary to isolate cells of interest for further analysis. Microfluidics has revolutionized the way in which these tests are conducted enabling, for example, the ability to detect cancer from a blood sample.
One of the most promising microfluidic techniques to separate and concentrate cells is called ...

Many sensors, such as flow sensors and those used in medical diagnostics, rely on microfluidic devices. However, mixing and pumping fluids becomes challenging because of the small size of these devices. As an alternative to traditional actuation methods, surface acoustic waves (SAWs) can be used to create fluid streaming.
Through a collaboration ...

Hematology analysis, the analysis of a blood sample to determine a variety of hematological parameters, is a major factor in diagnostic and treatment decisions for blood diseases. Accurate blood analysis requires counting and sorting different cells in a sample to measure their sizes and distributions. HORIBA Medical, a company that supplies ...

Veryst Engineering, a company that provides consulting in engineering design and product manufacturing, has collaborated with Nordson EFD, one of the leading manufacturers of precision dispensing systems, to optimize their static mixers.
Static mixers are inexpensive and efficient mechanisms for mixing laminar viscous fluids, where molecular ...

Professor Mark Reed and his team at Yale University are using COMSOL Multiphysics to develop a MEMS-based solution for detecting bacteria in blood. Called the aScreen, it will provide analyses speedily, accurately, and cost-effectively. Such a device would greatly help the food industry in improving meat quality and reducing the risk for ...

In many medical procedures and tests, it is necessary to isolate cells of interest for further analysis. Microfluidics has revolutionized the way in which these tests are conducted enabling, for example, the ability to detect cancer from a blood sample.
One of the most promising microfluidic techniques to separate and concentrate cells is called ...

Many sensors, such as flow sensors and those used in medical diagnostics, rely on microfluidic devices. However, mixing and pumping fluids becomes challenging because of the small size of these devices. As an alternative to traditional actuation methods, surface acoustic waves (SAWs) can be used to create fluid streaming.
Through a collaboration ...

Hematology analysis, the analysis of a blood sample to determine a variety of hematological parameters, is a major factor in diagnostic and treatment decisions for blood diseases. Accurate blood analysis requires counting and sorting different cells in a sample to measure their sizes and distributions. HORIBA Medical, a company that supplies ...

Microfluidics Module

Red Blood Cell Separation

Dielectrophoresis (DEP) occurs when a force is exerted on a dielectric particle as it is subjected to a nonuniform electric field. DEP has many applications in the field of biomedical devices used for biosensors, diagnostics, particle manipulation and filtration (sorting), particle assembly, and more.
The DEP force is sensitive to the size, ...

This application presents an example of pressure driven flow and electrophoresis in a 3D micro channel system. Researchers often use a device similar to the one in this model as an electrokinetic sample injector in biochips to obtain well-defined sample volumes of dissociated acids and salts and to transport these volumes.
Focusing is obtained ...

Emulsions consist of small liquid droplets immersed in an immiscible liquid and widely occur in the production of food, cosmetics, fine chemicals, and pharmaceutical products. The quality of the product is typically dependent on the size of the droplets. Simulating these processes can help in optimizing these droplets as well as other process ...

Although initially invented to be used in printers, inkjets have been adopted for other application areas, such as within the life sciences and microelectronics. Simulations can be useful to improve the understanding of the fluid flow and to predict the optimal design of an inkjet for a specific application.
The purpose of this application is to ...

This example describes the operation of a drug delivery system that supplies a variable concentration of a water soluble drug. A droplet with a fixed volume of water travels down a capillary tube at a constant velocity. Part of the capillary wall consists of a permeable membrane separating the interior of the capillary from a concentrated ...

Microlaboratories for biochemical applications often require rapid mixing of different fluid streams. At the microscale, flow is usually highly ordered laminar flow, and the lack of turbulence makes diffusion the primary mechanism for mixing.
While diffusional mixing of small molecules (and therefore of rapidly diffusing species) can occur in a ...

The contact angle of a two-fluid interface with a solid surface is determined by the balance of the forces at the contact point. In electrowetting the balance of forces at the contact point is modified by the application of a voltage between a conducting fluid and the solid surface.
In many applications the solid surface consists of a thin ...

At the macroscopic level, systems usually mix fluids using mechanical actuators or turbulent 3D flow. At the microscale level, however, neither of these approaches is
practical or even possible. This model demonstrates the mixing of fluids using laminar-layered flow in a MEMS mixer. This model analyzes the steady-state condition of the fluid flow ...

This model simulates an H-shaped micro-cell designed for controlled diffusive mixing. The cell puts two different laminar streams in contact for a controlled period of time. The contact surface is well-defined and, by controlling the flow rate, it is possible to control the amount of species that are transported from one stream to the other ...

Dielectrophoresis (DEP) occurs when a force is exerted on a dielectric particle as it is subjected to a nonuniform electric field. DEP has many applications in the field of biomedical devices used for biosensors, diagnostics, particle manipulation and filtration (sorting), particle assembly, and more.
The DEP force is sensitive to the size, ...

This application presents an example of pressure driven flow and electrophoresis in a 3D micro channel system. Researchers often use a device similar to the one in this model as an electrokinetic sample injector in biochips to obtain well-defined sample volumes of dissociated acids and salts and to transport these volumes.
Focusing is obtained ...

Emulsions consist of small liquid droplets immersed in an immiscible liquid and widely occur in the production of food, cosmetics, fine chemicals, and pharmaceutical products. The quality of the product is typically dependent on the size of the droplets. Simulating these processes can help in optimizing these droplets as well as other process ...

Although initially invented to be used in printers, inkjets have been adopted for other application areas, such as within the life sciences and microelectronics. Simulations can be useful to improve the understanding of the fluid flow and to predict the optimal design of an inkjet for a specific application.
The purpose of this application is to ...

This example describes the operation of a drug delivery system that supplies a variable concentration of a water soluble drug. A droplet with a fixed volume of water travels down a capillary tube at a constant velocity. Part of the capillary wall consists of a permeable membrane separating the interior of the capillary from a concentrated ...

Microlaboratories for biochemical applications often require rapid mixing of different fluid streams. At the microscale, flow is usually highly ordered laminar flow, and the lack of turbulence makes diffusion the primary mechanism for mixing.
While diffusional mixing of small molecules (and therefore of rapidly diffusing species) can occur in a ...

The contact angle of a two-fluid interface with a solid surface is determined by the balance of the forces at the contact point. In electrowetting the balance of forces at the contact point is modified by the application of a voltage between a conducting fluid and the solid surface.
In many applications the solid surface consists of a thin ...

At the macroscopic level, systems usually mix fluids using mechanical actuators or turbulent 3D flow. At the microscale level, however, neither of these approaches is
practical or even possible. This model demonstrates the mixing of fluids using laminar-layered flow in a MEMS mixer. This model analyzes the steady-state condition of the fluid flow ...

This model simulates an H-shaped micro-cell designed for controlled diffusive mixing. The cell puts two different laminar streams in contact for a controlled period of time. The contact surface is well-defined and, by controlling the flow rate, it is possible to control the amount of species that are transported from one stream to the other ...